The public-switched telephone network (PSTN) comprises: a large number of end switches for serving local subscriber lines and trunks; a smaller number of tandem switches for providing connections between end switches; a large plurality of analog and digital communication paths for interconnecting the end switches, and tandem switches; optional databases for storing information; and a common channel signaling (CCS) system overlay that transmits messages used by the switches for establishing call connections.
The CCS system comprises a plurality of inter-connected signal transfer points (STPs) that transmit messages among network nodes for establishing, managing, and releasing call paths in the PSTN. For identification purposes, each PSTN switch is assigned a discrete "point code" which identifies the switch within the network. Call connections are initiated by call "set-up" messages relayed among network nodes via the CCS system. For example, a two-party call generates several set-up messages including: an initial address message (IAM) formulated by an originating switch (that is, the switch from which the call originates); a line test message; and an answer message. The information contained in call set-up messages is critical for establishing call connections. Therefore, even minor message errors can result in a failed call, which is defined as call for which a network connection to a desired called party is not made. A significant number of failed call connections are the result of erroneous or, undelivered CCS messages.
In existing arrangements, call failure investigation begins after a predetermined number of calls originating from a particular switch over a pre-determined period of time fail, and a "trouble message" is sent by the switch to a maintenance operations support system. A maintenance OSS technician monitors the switch from which the trouble message was received (hereinafter, the "trouble switch"), and reviews a historical record of CCS messages relayed by the trouble switch in an attempt to determine the reasons for call failure. If it appears that the trouble switch is functioning properly, message segments relayed by other network nodes during the unsuccessful call attempts must be obtained directly from those nodes for review and analysis. It is common for a call to generate a substantial number of messages which are relayed to a plurality of network nodes before the call attempt fails. In such cases, the technician must perform the arduous, and error-prone task of retrieval and reconstruction of network signaling messages to determine a cause, and solution for the signaling errors that resulted in call failure.
The inability to easily obtain a network perspective of signaling messages relayed for the establishment of a call connection unduly increases the time required for call failure investigations, and resolutions. Therefore, there is a need in the art for a method and system for efficiently monitoring signaling messages relayed in a network for establishing a call connection.